Recent advances in free-space optical communications (FSOC) have led to mobile, long distance communication data links at distances exceeding 200 km with data rates of 10 Gbps or greater. However, FSOC data links are highly directional and may require a multi-step pointing, acquisition, and tracking, (PAT) process to establish and/or maintain the data links. In some instances, beacons may be used to guide the pointing of a data beam. A challenge in the PAT process may be beacon acquisition at long distances and/or under challenging weather conditions, such as light haze, bright solar backgrounds, or the like.
FSOC has been increasingly viewed as a potential alternative technology to conventional radio frequency and microwave communications, providing substantially increased data throughput, relief from spectrum planning, and improvements in link security. One of the main challenges in fielding FSOC systems are the deleterious effects introduced by atmospheric turbulence. These include: (1) beam broadening beyond natural diffraction effects as the beam propagates from the transmitter to the receiver, (2) spot blurring and broadening in the focal plane at the receiving aperture with increased turbulence, and (3) intensity fades known as scintillation due to interference effects as a result of the aberrated beam wavefront. Each of these effects introduces substantial link budget penalties for FSOC systems.